Substrate processing apparatus and reaction container

ABSTRACT

A substrate processing apparatus comprises a reaction chamber which is to accommodate stacked substrates, a gas introducing portion, and a buffer chamber, wherein the gas introducing portion is provided along a stacking direction of the substrates, and introduces substrate processing gas into the buffer chamber, the buffer chamber includes a plurality of gas-supply openings provided along the stacking direction of the substrates, and the processing gas introduced from the gas introducing portion is supplied from the gas-supply openings to the reaction chamber.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a substrate processing apparatusand a reaction container, more particularly, to a substrate processingapparatus and a reaction container used in one step of producing processof a semiconductor device for processing a substrate in a reactionchamber, and more particularly, to an improvement of a gas introducingportion which supplies gas to a substrate.

[0003] 2. Description of the Related Art

[0004] A conventional technique for processing a substrate in a reactionchamber by a CVD (Chemical Vapor Deposition) method or an ALD (AtomicLayer Deposition) method will be briefly explained with reference toFIG. 14 while taking a vertical type substrate processing apparatus asan example.

[0005]FIG. 14 is a schematic sectional view of the inside of a reactiontube which is a reaction chamber in the conventional vertical typesubstrate processing apparatus.

[0006] A plurality of wafers 107 are stacked on a boat 108 as substratesto be processed. The boat 108 is inserted into a reaction tube 106. Agas nozzle 101 as a gas introducing portion for processing the wafers107 in the reaction tube 106 is provided in the reaction tube 106.

[0007] The gas nozzle 101 is provided with a plurality of gas nozzleholes 103 (five in the example shown in FIG. 14). With this arrangement,processing gas flows into the gas nozzle 101 from a gas introducingopening 105, and is supplied to the wafers 107 from the gas nozzle holes103.

[0008] The gas supplied to each wafer 107 passes through a process forforming a desired film on the wafer 107 and then, is discharged out fromthe reaction tube 106 through an exhaust opening 118.

[0009] However, when all of the gas nozzle holes 103 provided in the gasnozzle 101 have the same opening areas, there is a problem that a flowrate and flow velocity of gas supplied from the gas nozzle holes 103 tothe wafers 107 are reduced from an upstream side closer to the gasintroducing opening 105 toward a downstream side further from theopening 105.

[0010] That is, if the apparatus for collectively processing theplurality of wafers 107 shown in FIG. 14 is considered from a viewpointof gas supply with respect to each of the wafers, it seems that the gasnozzle 101 supplies gas uniformly to the wafers 107, but in reality, adifference in the gas flow rate or flow velocity is generated, and thegas is not supplied to all of the wafers 107 under the same conditions.

[0011] For example, if the five gas nozzle holes 103 provided in the gasnozzle 101 are defines as a first hole, a second hole, . . . and a fifthhole from the upstream side closer to the gas introducing opening 105 ofthe gas nozzle 101 toward the downstream further from the opening 105,and if the flow rates of gas supplied from the respective gas nozzleholes 103 are defined as q1, q2 . . . q5, a relation of q1>q2> . . . >q5is established.

[0012] Concerning the flow velocities of gas also, a velocity of gasfrom the first gas nozzle holes 103 is the fastest, and velocities ofgas from the second, third, . . . are gradually reduced.

[0013] As a result, the flow rates and flow velocities of gas suppliedto the wafers 107 become nonuniform.

[0014] Therefore, in the process of wafers which largely depends of asupply amount of gas, the film forming states of the stacked wafers 107become nonuniform.

[0015] Referring back to FIG. 14, a cause of the nonuniformity of thesupply amount of gas will be considered.

[0016] In the gas nozzle 101 in a state in which gas is supplied to thewafers 107, a gas flow rate between the introducing opening 105 and thefirst gas nozzle hole 103 is defined as q00 and a gas pressuretherebetween is defined as p0. Next, a gas flow rate between the firstand second gas nozzle holes 103 is defined as q01 and a gas pressuretherebetween is defined as p1. Similarly, a gas flow rate between then−1-th and n-th gas nozzle holes 103 is defined as q0(n−1) and a gaspressure therebetween is defined as pn−1.

[0017] A flow rate of gas injecting from the n-th gas nozzle hole 103 isdefined as qn.

[0018] At that time, gas flow rates qn (n=1, 2, . . . ) injecting fromthe plurality of gas nozzle holes 103 provided from the upstream side tothe downstream side and having the same opening areas are reduced fromthe upstream gas nozzle hole toward the downstream gas nozzle hole asshown in the following expression (1):

q1>q2> . . . >qn−1>qn  (1).

[0019] This is because, in the case of gas flowing from the upstreamside toward the downstream side through the gas nozzle 101, its gas flowrate q0(n−1) is reduced by a gas flow rate qn injecting from the gasnozzle hole 103 when the gas passes through the gas nozzle hole 103, andthe gas flows toward a next gas nozzle hole. A flow rate of gas afterthe gas passed through the gas nozzle hole 103 is reduced from theupstream side toward the downstream side as shown in the followingexpression (2):

q0n=q0(n−1)−qn  (2)

[0020] At that time, a gas concentration of fluid in the gas nozzle 101is reduced by a flow rate of gas injecting from the gas holes from theupstream side toward the downstream side. Since there is a correlationbetween the gas concentration and gas pressure, a gas pressure pn at alocation in the gas nozzle 101 corresponding to the gas nozzle hole 103is reduced from the upstream side toward the downstream side as shown inthe following expression (3):

p1>p2> . . . >pn−1>pn  (3)

[0021] Therefore, flow rates of gas injecting from the respective gasnozzle holes 103 do not become equal to each other. If an opening areaof the gas nozzle hole 103 is defined as S, a flow velocity V of gasinjecting from the gas nozzle hole is expressed as shown in thefollowing expression (4):

V=qn/S  (4)

[0022] Since the flow rates of gas injected from the respective gasnozzle holes 103 are not equal to each other, if the opening areas ofthe nozzle holes are the same, flow velocities of gas injected from therespective gas nozzle holes 103 become different. In the above-describedconventional gas nozzle 101, since the flow rates and flow velocities ofgas injected from the respective gas nozzle holes 103 are different, itis considered that gas can not be supplied to the wafers uniformly.

[0023] To solve the above problem, two conventional solutions have beenproposed.

[0024] According to a first solution, opening areas of the gas nozzlehole 103 are increased from the upstream side toward the downstreamside, and a gas flow rate which is reduced toward the downstream side issupplemented by increasing the opening area. However, if the gas flowrates are equalized by adjusting the opening areas, the gas flowvelocities are adversely varied depending upon the size of the openingarea. Therefore, gas injecting from the gas nozzle holes 103 isnonuniform in the flow velocity.

[0025] According to a second solution, a capacity of the gas nozzleitself is increased to such a degree that such a large amount of gasthat the injecting amount can be ignored is stored so that even if gasis injected from the gas nozzle holes 103 from the upstream side towardthe downstream side, gas pressures in the gas nozzle 101 at locationscorresponding to the respective gas nozzle holes 103 are not changed,thereby equalizing the flow rates of gas injecting from the gas nozzleholes 103. However, if the capacity of the gas nozzle itself isincreased to such a size that the gas pressure in the gas nozzle 101 isnot affected by the gas injecting amount, since there is limitation inspace of the reaction chamber which accommodates the gas nozzle, this isnot practical.

[0026] The above problem is not limited to a wafer, and a substrate ingeneral also has the same problem.

SUMMARY OF THE INVENTION

[0027] Thereupon, it is a main object of the present invention toprovide, from a viewpoint different from the above structure, asubstrate processing apparatus capable of achieving the uniformity ofprocess between substrates by uniformly supplying gas.

[0028] According to a first aspect of the present invention, there isprovided a substrate processing apparatus, comprising:

[0029] a reaction chamber which is to accommodate stacked substrates,

[0030] a gas introducing portion, and

[0031] a buffer chamber, wherein

[0032] the gas introducing portion is provided along a stackingdirection of the substrates, and introduces substrate processing gasinto the buffer chamber,

[0033] the buffer chamber includes a plurality of gas-supply openingsprovided along the stacking direction of the substrates, and theprocessing gas introduced from the gas introducing portion is suppliedfrom the gas-supply openings to the reaction chamber.

[0034] According to a second aspect of the present invention, there isprovided a substrate processing apparatus, comprising:

[0035] a reaction chamber which is to accommodate stacked substrates,

[0036] a plurality of buffer chambers, and

[0037] a plurality of gas introducing portions for respectivelyintroducing substrate processing gases to the buffer chambers, wherein

[0038] the buffer chambers respectively include a plurality ofgas-supply openings provided in a stacking direction of the substrates,and the substrate processing gas introduced from each of the gasintroducing portions is supplied to the reaction chamber from thegas-supply openings of each of the buffer chambers.

[0039] According to a third aspect of the present invention, there isprovided a reaction container, comprising:

[0040] a reaction chamber which is to accommodate stacked substrates,

[0041] a plurality of buffer chambers, and

[0042] a plurality of gas introducing portions for respectivelyintroducing substrate processing gases to the buffer chambers, wherein

[0043] the buffer chambers respectively include a plurality ofgas-supply openings provided in a stacking direction of the substrates,and the substrate processing gas introduced from each of the gasintroducing portions is supplied to the reaction chamber from thegas-supply openings of each of the buffer chambers.

[0044] According to a forth aspect of the present invention, there isprovided a reaction container, comprising:

[0045] a reaction chamber which is to accommodate stacked substrates,

[0046] a gas introducing portion, and

[0047] a buffer chamber, wherein

[0048] the gas introducing portion is provided along a stackingdirection of the substrates, and introduces substrate processing gasinto the buffer chamber,

[0049] the buffer chamber includes a plurality of gas-supply openingsprovided along the stacking direction of the substrates, and theprocessing gas introduced from the gas introducing portion is suppliedfrom the gas-supply openings to the reaction chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and further objects, features and advantages of thepresent invention will become more apparent from the following detaileddescription taken in conjunction with the accompanying drawings,wherein:

[0051]FIG. 1 is a schematic sectional view of a inside of a reactiontube of a substrate processing apparatus according to a first embodimentof the present invention;

[0052]FIG. 2A is a schematic lateral sectional view of a reaction tubeof a substrate processing apparatus according to a first embodiment ofthe present invention;

[0053]FIG. 2B is a longitudinal sectional view taken along a line aa′ ofFIG. 2A;

[0054]FIG. 3A is a perspective view of a gas nozzle according to a firstembodiment of the present invention;

[0055]FIG. 3B is a perspective view of a buffer chamber according to afirst embodiment of the present invention;

[0056]FIG. 4 is a schematic view for explaining a mechanism of avertical type substrate processing apparatus according to embodiments ofthe present invention;

[0057]FIG. 5A is a view showing an outward appearance of a reaction tubeof a substrate processing apparatus according to a second embodiment ofthe present invention;

[0058]FIG. 5B is a schematic longitudinal sectional view of a reactiontube of a substrate processing apparatus according to a secondembodiment of the present invention;

[0059]FIG. 5C is a schematic longitudinal partial sectional view of areaction tube of a substrate processing apparatus according to a secondembodiment of the present invention;

[0060]FIG. 6 is a lateral sectional view taken along a line A-A of FIG.5A;

[0061]FIG. 7 is a lateral sectional view of a reaction tube of asubstrate processing apparatus according to a third embodiment of thepresent invention;

[0062]FIG. 8 is a lateral sectional view of a reaction tube of asubstrate processing apparatus according to a forth embodiment of thepresent invention;

[0063]FIG. 9 is a lateral sectional view of a reaction tube of asubstrate processing apparatus according to a fifth embodiment of thepresent invention;

[0064]FIG. 10 is a lateral partial sectional view of a reaction tube ofa substrate processing apparatus according to a sixth embodiment of thepresent invention;

[0065]FIG. 11 is a lateral partial sectional view of a reaction tube ofa substrate processing apparatus according to a seventh embodiment ofthe present invention;

[0066]FIG. 12 is a lateral partial sectional view of a reaction tube ofa substrate processing apparatus according to a eighth embodiment of thepresent invention;

[0067]FIG. 13 is a lateral sectional view of a reaction tube of asubstrate processing apparatus according to a ninth embodiment of thepresent invention; and

[0068]FIG. 14 is a schematic sectional view of a inside of a reactiontube of a substrate processing apparatus according to a conventionaltechnique.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] According to a preferred embodiment of the present invention,there is provided a substrate processing apparatus comprises

[0070] a reaction chamber which is to accommodate stacked substrates,

[0071] a gas introducing portion, and

[0072] a buffer chamber, wherein

[0073] the gas introducing portion is provided along a stackingdirection of the substrates, and introduces substrate processing gasinto the buffer chamber,

[0074] the buffer chamber includes a plurality of gas-supply openingsprovided along the stacking direction of the substrates, and theprocessing gas introduced from the gas introducing portion is suppliedfrom the gas-supply openings to the reaction chamber.

[0075] With this structure, the substrate processing apparatus accordingto the present invention, nonuniform flow velocity of gas supplied fromthe gas introducing portion can be equalized in the buffer chamber, andgas can be supplied to the stacked substrates uniformly.

[0076] Preferably, opening areas of the gas-supply openings provided inthe buffer chamber are substantially equal to each other.

[0077] It is possible to further equalize the gas supply to thesubstrates by providing the gas-supply openings having the same openingareas.

[0078] Preferably, the buffer chamber is provided therein withelectrodes for generating plasma.

[0079] Since the electrodes for generating plasma are provided in thebuffer chamber, active species are produced by plasma at a locationclose to the substrates and in a state in which pressure is uniform, anduniform and more active species can be supplied to the substrates.

[0080] Next, embodiments of the present invention will be explained withreference to the drawings.

[0081] First, as an example of process for a substrate carried out inthe embodiment of the invention, film forming processing using the CVDmethod and the ALD method will briefly be explained based on acomparison the methods.

[0082] In the CVD method, one kind (or more kinds) of gases which areraw material used for forming a film are mixed and supplied onto asubstrate under a certain film forming condition (temperature, time orthe like), the gas is adsorbed and reacted on the substrate using bothvapor-phase reaction and surface reaction, or only surface reaction,thereby forming a film.

[0083] According to the ALD method, two kinds (or more kinds) of gaseswhich are raw material used for forming a film are alternately suppliedonto a substrate one kind gas by one kind gas under a certain filmforming condition (temperature, time or the like), the gas is adsorbedin one atomic layer unit, and a film is formed utilizing the surfacereaction.

[0084] That is, when a SiN (silicon nitride) film is to be formed forexample, in the case of the ALD method, DCS (dichlorsilane) and NH₃(ammonia) are used for carrying out chemical reaction to be utilized,and a film having high quality can be formed at a low temperature of 300to 600C.°. Whereas, in the case of a normal CVD method, a film formingtemperature is relatively high as high as 600 to 800C.°. In the case ofthe ALD method, a plurality of kinds of reaction gases are alternatelysupplied one kind gas by one kind gas (not at the same time), and in thecase of the normal CVD method, a plurality of kinds of gases aresupplied at the same time. In the ALD method, a film thickness iscontrolled based on the number of cycles of supply of reaction gas(assuming that a film forming velocity is 1 Å/cycle for example, when afilm of 20 Å is to be formed, the processing is carried out through 20cycles), and in the CVD method, a film thickness is controlled based ontime.

[0085] An embodiment of the present invention will be explained withreference to FIGS. 1 to 13.

[0086] The same elements are designated with the same symbols in FIGS. 1to 13.

[0087] First, an outline of a mechanism of a vertical type substrateprocessing apparatus of each of embodiments of the present inventionwill be briefly explained using FIG. 4.

[0088]FIG. 4 shows an outward appearance of an example of a verticaltype substrate processing apparatus in which a plurality of wafers whichare substrates to be processed and which have diameter of 200 mm areloaded in a reaction tube which is a reaction chamber and made ofquartz, and films are formed by the CVD method or the ALD method whichis one of the CVD method as processing method.

[0089] The vertical type substrate processing apparatus has a body 60and a utility portion 61 which supplies electric power or the like tothe body 60.

[0090] In the body 60, there are provided a reaction tube 6 as avertical type reaction chamber for processing wafers, and a heater 16for appropriately heating the reaction tube 6. A boat 8 for loading andunloading the wafers into and from the reaction tube 6, and a boatelevator 36 for vertically moving the boat 8 are disposed below thereaction tube 6.

[0091] If it is necessary to produce plasma in the reaction tube 6,electrodes 52 are provided in the reaction tube 6, high frequencyelectric power is applied to the electrodes 52 from a high frequencypower supply 51 through an RF matching unit 53.

[0092] Further, provided in the body 60 are cassette shelves 34 fortemporarily storing cassettes in which wafers to be supplied to the boat8 are accommodated, and a wafer transfer apparatus 38 for supplyingwafers which are not yet processed (pre-process wafers, hereinafter)from the cassette shelves 34 to the boat 8 and for transferring outwafers which were processed (post-process wafers, hereinafter).

[0093] A cassette loader 35 transfers a cassette 32 between the cassetteshelves 34 and an I/O stage 33 which receives and delivers the cassette32 of the wafer from and to outside.

[0094] The I/O stage 33 is disposed on a front surface of the apparatus,and delivers and receives the cassette 32 accommodating wafers to andfrom outside.

[0095] The operation of the above-described vertical type substrateprocessing apparatus will be explained briefly.

[0096] The cassettes 32 accommodating the wafers are set to the I/Ostage 33.

[0097] The cassettes 32 set in the I/O stage 33 are transferred to thecassette shelves 34 by the cassette loader 35 in succession.

[0098] In the cassette 32, 25 wafers are accommodated.

[0099] The wafer transfer apparatus 38 transfers the wafers out from thecassette shelves 34 and transfers the same to the quartz boat 8. Since100 wafers can be loaded into the boat 8, the transfer operation by thewafer transfer apparatus 38 is repeated several times.

[0100] If the transfer operation of the wafers to the boat 8 iscompleted, the boat 8 is moved upward by the boat elevator 36 andinserted into the reaction tube 6 and then, the inside of the reactiontube 6 is held air-tightly.

[0101] The gas is exhausted from the reaction tube 6 through an exhaustopening (not shown) using a pump, and if a pressure in the reaction tube6 reaches a predetermined value, the boat 8 is rotated by a rotatingmechanism (not shown), and film-forming processing gas of a certain flowrate is supplied into the reaction tube 6. A pressure of the suppliedprocessing gas is maintained at a constant value by a pressure adjustingmechanism (not shown). At that time, the wafers in the reaction tube 6are maintained at a predetermined temperature.

[0102] The process for forming films on the wafers is proceeded in thismanner, and further details thereof will be described later.

[0103] If the film is formed by a plasma CVD method or the ALD method,high frequency electric power is applied to the electrodes 52 from thehigh frequency power supply 51 through the RF matching unit 53, plasmais produced in the film-forming gas, and the film-forming gas isactivated. This activating operation will also be described later.

[0104] If the process for forming film is completed, the wafer boat 8 ismoved down from the reaction tube 6 by the boat elevator 36, the waferboat 8 is transferred to the I/O stage 33 through the wafer transferapparatus 38, the cassette shelves 34 and the cassette loader 35, andtransferred out from the apparatus.

[0105] Next, embodiments using the above-described vertical typesubstrate processing apparatus will be explained.

[0106] (First Embodiment)

[0107] Embodiment Using CVD Method for Film Forming Process

[0108]FIG. 2A is a schematic lateral sectional view of the reaction tubein the vertical type substrate processing apparatus according to thisembodiment, and FIG. 2B is a vertical sectional view taken along a linea-a′ in FIG. 2A.

[0109] In FIG. 2A, a heater 16 is provided on an outer periphery of thereaction tube 6 which is a vertical type reaction chamber. A pluralityof wafers 7 as substrates to be processed are stacked and placed in thereaction tube 6. In an arc space between the wafers 7 and an inner wallof the reaction tube 6, a buffer chamber 17 is provided on an inner wallof the reaction tube 6 from its lower portion to its upper portion alonga stacking direction of the wafers 7. Buffer chamber holes 3 asgas-supply openings are provided in an end of a wall of the bufferchamber 17 which is adjacent to the wafer 7. The buffer chamber holes 3are opened toward a center of the reaction tube 6.

[0110] An end of the buffer chamber 17 which is opposite from the bufferchamber holes 3 is provided with a gas nozzle 2 formed in the gasintroducing portion from the lower portion to the upper portion of thereaction tube 6 along the stacking direction of the wafers 7. The gasnozzle 2 is provided with a plurality of gas nozzle holes 4.

[0111] As shown in FIG. 2B, an outer periphery of the reaction tube 6 iscovered with the heater 16. The reaction tube 6 is supported on afurnace opening flange 25. A furnace opening of the furnace openingflange 25 is air-tightly closed with a furnace opening cap 27.

[0112] The boat 8 is provided in a central portion in the reaction tube6. The plurality of wafers 7 are placed in the boat 8 at equal distancesfrom one another in a multistage manner. The boat 8 can come into and goout from the reaction tube 6 by the boat elevator. In order to enhancingthe uniformity of the processing, the boat 8 is provided at its lowerportion with a rotating mechanism 15 for rotating the boat 8.

[0113] When the boat 8 enters the reaction tube 6 to form films on thewafers 7, the wafers 7 placed in the multistage manner are placed at anequal distance from the buffer chamber 17.

[0114] The buffer chamber 17 is provided along the inner wall of thereaction tube 6, the gas nozzle 2 is disposed in the buffer chamber 17from the lower portion to the upper portion of a side surface of thereaction tube 6, and a portion of the gas nozzle 2 at the lower portionbecomes a gas introducing opening 5.

[0115] The gas nozzle 2 and the buffer chamber 17 are provided with thegas nozzle holes and the buffer chamber holes, respectively. Examples ofopening states of these holes will be explained using FIGS. 3A and 3B.

[0116]FIG. 3A is a perspective view of the gas nozzle shown in FIGS. 2Aand 2B. FIG. 3B is a perspective view of the buffer chamber also shownin FIGS. 2A and 2B.

[0117] The gas nozzle 2 shown in FIG. 3A is a pipe having a circularcross section. The gas nozzle holes 4 are straightly arranged in a sidesurface of the gas nozzle 2 from its substantially uppermost portion toa bottom of the buffer chamber 17 from an upstream side toward adownstream side of gas flow. Opening areas of the gas nozzle holes 4 areincreased from the upstream side (lower portion in FIG. 3A) toward thedownstream side (upper portion in FIG. 3A) as viewed from the gasintroducing opening.

[0118] The buffer chamber 17 shown in FIG. 3B is a pipe having an arccross section. The buffer chamber holes 3 having the same opening areasare straightly arranged in an end of a curve inner surface of the bufferchamber 17 along the stacking direction of the wafers 7.

[0119] Referring back to FIG. 2B, the reaction tube 6 is provided at itslower portion with an exhaust opening 18 connected to an exhaust pump(not shown).

[0120] The film forming process by the CVD method on the wafer 7 in thereaction tube 6 will be explained with reference to FIGS. 2A and 2B.

[0121] The processing gas which is raw material is supplied to the gasnozzle 2 from the gas introducing opening 5. The gas nozzle 2 isprovided with the plurality of gas nozzle holes 4, and the gas nozzle 2injects gas into the buffer chamber 17. As described as the conventionalsolution, however, it is difficult to uniform the flow rate and the flowvelocity of gas injected from the plurality of gas nozzle holes 4 bycontrolling only the opening areas of the gas nozzle holes 4.

[0122] Thereupon, in the present invention, the opening areas of the gasnozzle holes 4 are increased from the upstream side toward thedownstream side. With this arrangement, gas of substantially the sameflow rate is injected from each of the gas nozzle holes 4 although thereis a difference in the flow velocity of gas. Then, the gas injected fromthe gas nozzle holes 4 is not injected into the reaction tube 6, but thegas once injected and introduced into the buffer chamber 17, and theflow velocities of the gas are uniformed.

[0123] That is, the gas injected from each the gas nozzle holes 4 in thebuffer chamber 17 is moderated in the particle velocity of gas in thebuffer chamber 17 and then, is injected into the reaction tube 6 fromthe buffer chamber holes 3. During that time, kinetic energies of thegas injected from the gas nozzle holes 4 are exchanged and thus, whenthe gas is injected from the buffer chamber holes 3, gas having theuniform flow rate and flow velocity can be injected.

[0124] The equalizing operation of the gas supply amount in the bufferchamber 17 will be explained in more detail using FIG. 1.

[0125]FIG. 1 is a schematic sectional view showing a relation betweenthe gas nozzle, the buffer chamber and the reaction tube in the reactiontube of the vertical type substrate processing apparatus of theinvention.

[0126] In FIG. 1, the buffer chamber 17 is provided in the reaction tube6. The gas nozzle 2 is disposed in the buffer chamber 17, and thereaction tube 6 is provided with the exhaust opening 18 for exhaustinggas in the reaction tube 6 to outside.

[0127] In the reaction tube 6, the boat 8 having wafers 7 (five wafersin FIG. 1) is provided adjacent to the buffer chamber 17.

[0128] The gas nozzle 2 and the buffer chamber 17 are respectivelyprovided with the gas nozzle holes 4 and the buffer chamber holes 3(five each in FIG. 1). The opening areas of the gas nozzle holes 4 areincreased from the upstream side toward the downstream side as viewedfrom the gas introducing opening 5 so that the injecting amounts of gasfrom the gas nozzle holes 4 become the same.

[0129] With this structure, if the gas nozzle holes 4 of the gas nozzle2 are respectively defined as the first, second . . . fifth gas nozzlehole from the upstream side closer to the introducing opening 5 towardthe downstream side further from the introducing opening 5, and if theflow rates of gas supplied from the respective gas nozzle holes 4 arerespectively defined as Q1, Q2 . . . Q5, it is possible to obtain astate of Q1=Q2= . . . =Q5.

[0130] In the flow velocities of gas as explained in the conventionalsolution, however, gas from the first gas nozzle hole 4 is the fastest,and the flow velocity is gradually reduced in the order of the second,third, forth and fifth gas nozzle holes.

[0131] Gas having the same flow rates but different flow velocities Q1to Q5 is once introduced into the buffer chamber 17. During that time,gas having the flow velocities Q1 to Q5 is uniformed in flow velocity byexchanging kinetic energies, and a pressure in the buffer chamber 17 issubstantially equalized.

[0132] As a result, if the flow rates of gas injected from the bufferchamber holes 3 are respectively defined as R1, R2 . . . R5, even if thebuffer chamber holes 3 have the same opening areas, since the pressurein the buffer chamber 17 is uniform, a state of R1=R2= . . . =R5 can beobtained, and the flow velocities become equal to each other.

[0133] Further, the opening positions of the buffer chamber holes 3 havethe same pitches as the wafers 7 which are respectively adjacent to thebuffer chamber holes. 3, and the gas is supplied to gaps between thewafers 7. Therefore, gas having uniform flow velocities and flow ratescan efficiently be supplied to the wafers 7 preferably.

[0134] Since the gas having uniform flow velocities and flow rates canefficiently be supplied to the wafers 7, the film forming states of thewafers 7 are equalized, and the processing speed of the wafers 7 canlargely be enhanced.

[0135] Although the gas nozzle and the buffer chamber are described inthe above explanation based on the CVD method, the invention can also beapplied based on the ALD method also.

[0136] (Second Embodiment)

[0137] Embodiment Using ALD Method for Film Forming Process

[0138] An embodiment for forming films by the ALD method will beexplained concretely.

[0139] When films are formed on the wafers 7 by the ALD method also, theabove-described vertical type substrate processing apparatus can beused. In the case of the ALD method, however, if it is required toactivate the processing gas by plasma or the like, an apparatus and anoperation required for this process are added.

[0140] A case for forming films by the ALD method will be explainedbelow using FIGS. 5A, 5B and 5C and FIG. 6.

[0141]FIGS. 5A, 5B and 5C show, from a side, an outward appearance andthe inside of the reaction tube which is the reaction chamber in thevertical type substrate processing apparatus of the invention used forforming films by the ALD method. FIG. 6 is a lateral sectional viewtaken along a line A-A.

[0142]FIG. 5A shows the outward appearance of the reaction chamber.FIGS. 5B and C are vertical sectional views of the reaction chamber. Inthe drawings, connected portions of the furnace opening flange withrespect to the heater, the wafers, the boat and the reaction tube, aswell as the boat rotating mechanism are omitted.

[0143] In FIG. 6, the reaction tube 6 is provided at its outer peripherywith a heater 16, and the plurality of wafers 7 as substrates to beprocessed are stacked inside the reaction tube 6. The buffer chamber 17is provided in the arc space between the wafers 7 and the inner wall ofthe reaction tube 6 along the stacking direction of the wafers 7 to theinner wall of the reaction tube 6, and the buffer chamber holes 3 areprovided in the end of the wall which is adjacent to the wafers.

[0144] The reaction tube 6 is provided at its lower portion with theexhaust opening 18.

[0145] In the reaction tube explained in FIG. 2A, the gas nozzle isprovided in the end which is opposite from the buffer chamber hole inthe buffer chamber. In this embodiment, a gas supply chamber 43 isprovided as the gas introducing portion in the reaction tube instead ofthe gas nozzle. The gas supply chamber 43 is provided at its lowerportion with the gas introducing opening 5.

[0146] A partition wall between the gas supply chamber 43 and the bufferchamber 17 is provided with gas supply chamber holes 47 having the samestructure as that of the gas nozzle holes provided in theabove-described gas nozzle. The opening positions of the buffer chamberholes 3 provided in the buffer chamber 17 have the same pitches as thoseof the adjacent wafers 7.

[0147] As a result, like the first embodiment, gas is once introducedfrom the gas introducing portion, and gas can be supplied to the stackedwafers 7 uniformly.

[0148] In this embodiment, the electrode 52 is disposed in the bufferchamber 17 such that the electrode 52 is protected by anelectrode-protecting tube 50 from its upper portion to lower portion.The electrode 52 is connected to the high frequency power supply 51through the RF matching unit 53. As a result, the electrode 52 cangenerate plasma 14 in the buffer chamber 17.

[0149] In addition, in this embodiment, a reaction gas buffer chamber 42is provided on an inner wall of the reaction tube 6 at a location awayfrom the opening of the buffer chamber hole 3 through 120° along theinner periphery of the reaction tube 6. This reaction gas buffer chamber42 contains gas different from that contained in the buffer chamber 17.When the films are to be formed by the ALD method, the reaction gasbuffer chamber 42 and the buffer chamber 17 supply different kinds ofgases to the wafers 7 alternately.

[0150] Like the buffer chamber 17, the reaction gas buffer chamber 42has reaction gas buffer chamber holes 48 with the same pitches atlocations adjacent to the wafers. The reaction gas buffer chamber 42 isprovided at its lower portion with a reaction gas introducing opening45. Unlike the buffer chamber 17, the reaction gas buffer chamber 42does not have the gas supply chamber 43 and the electrode 52. Openingareas of the reaction gas buffer chamber holes 48 are increased from theupstream side toward the downstream side.

[0151] The reaction tube 6 is provided at its lower portion with theexhaust opening 18. When different kinds of gases are alternatelysupplied to the wafers 7 to form films by the ALD method, the exhaustopening 18 can exhaust inside gas from the reaction tube 6.

[0152]FIG. 5A shows an outward appearance and the inside (shown withbroken lines) of the reaction tube 6 as viewed from a front surface ofthe buffer chamber 17.

[0153] The buffer chamber 17 is provided in the reaction tube 6 such asto extend from its upper portion to lower portion. The gas supplychamber 43 is provided adjacent to the buffer chamber 17. The electrode52 covered with the electrode-protecting tube 50 is disposed in thebuffer chamber 17 from its upper portion to lower portion. The gassupply chamber 43 is provided at its lower portion with the gasintroducing opening 5.

[0154] This electrode-protecting tube 50 can be inserted into the bufferchamber 17 in a state in which the thin and long electrode 52 isisolated from atmosphere in the buffer chamber 17. Here, since theinside has the same atmosphere as outside air, the electrode 52 insertedinto the electrode-protecting tube 50 is oxidized by heat from theheater. Therefore, an inert gas purging mechanism is provided in theelectro-deprotecting tube 50 for charging or purging inert gas such asnitrogen to suppress the oxygen concentration to sufficiently low level.

[0155] The reaction gas buffer chamber 42 is provided in the reactiontube 6 along its inner wall from its upper portion to lower portion awayfrom the buffer chamber 17. The reaction gas buffer chamber 42 isprovided at its lower portion with the reaction gas introducing opening45.

[0156] The reaction tube 6 is provided at its lower portion with theexhaust opening 18 along the inner wall of the reaction tube 6 at alocation opposed from the reaction gas buffer chamber 42 with respect tothe buffer chamber 17.

[0157]FIG. 5B shows the inside of the reaction tube 6 as viewed fromfront surfaces of the buffer chamber holes 3 and the reaction gas bufferchamber holes 48.

[0158] In the reaction tube 6, the buffer chamber 17 and the gas supplychamber 43 adjacent to the buffer chamber 17 extend from the upperportion to the lower portion in the reaction tube 6. The buffer chamberholes 3 having the same pitches are provided at positions adjacent tothe wafers (not shown) from the upper portion to the lower portion inthe buffer chamber 17. The buffer chamber holes 3 have the same openingareas in the wall of the buffer chamber 17 having the same thickness.

[0159] The reaction gas buffer chamber 42 is provided in the reactiontube 6 along its inner wall from its upper portion to lower portion awayfrom the buffer chamber 17. The reaction gas buffer chamber holes 48having the same pitches are provided adjacent to the wafers (not shown)from the upper portion to the lower portion in the reaction gas bufferchamber 42. The opening areas of the reaction gas buffer chamber holes48 are increased from the upstream side toward the downstream side, fromthe lower portion to the upper portion in FIGS. 5A, 5B and 5C.

[0160]FIG. 5C is a vertical sectional view of the reaction tube 6 asviewed from front surfaces of the gas supply chamber holes 47 providedin the gas supply chamber 43.

[0161] The gas supply chamber 43 is provided in the reaction tube 6 fromthe upper portion to the lower portion adjacent to the buffer chamber17. A partition wall between the buffer chamber 17 and the gas supplychamber 43 is provided with the gas supply chamber holes 47 from theupper portion to a location lower than the lower portion where the gassupply chamber holes 47 are adjacent to the wafers (not shown). Thereason why the gas supply chamber holes 47 are opened up to thelowermost end of the buffer chamber 17 is that stagnation of gas is notgenerated in the buffer chamber 17.

[0162] Like the gas nozzle holes provided in the gas nozzle explained inFIG. 3A, the opening areas of the gas supply chamber holes 47 areincreased from the upstream side toward the downstream side of the gasflow.

[0163] Here, the film forming operation on the wafers 7 in the reactiontube 6 by the ALD method will be explained with reference to FIGS. 5A,5B, 5C and 6.

[0164] In this film forming example, active species of ammonia (NH₃) anddichlorsilane (SiH₂Cl₂) are alternately supplied as processing gas, andSiNx film (silicon nitride film) is formed by an atomic layerfilm-forming method.

[0165] First, 100 wafers 7 are loaded into the reaction tube 6, and theinside of the reaction tube 6 is brought into the air-tight state andmaintained in this state. The reaction tube 6 is exhausted by a pump(not shown) through an exhaust pipe, and a temperature in the reactiontube 6 is constantly maintained in a range of 300 to 600° C. byadjusting the temperature using the heater 16.

[0166] The supply of ammonia to the gas supply chamber 43 from the gasintroducing opening 5 is started.

[0167] The opening areas of the gas supply chamber holes 47 provided inthe gas supply chamber 43 are gradually increased from the upstream sidetoward the downstream side of the gas flow so that the flow rates ofammonia injected into the buffer chamber 17 from the gas supply chamber43 become the same.

[0168] Therefore, the flow velocity of ammonia injected into the bufferchamber 17 through the gas supply chamber holes 47 is fast at theupstream side and slow at the downstream side, but the flow rates of theammonia through all of the gas supply chamber holes 47 are the same.

[0169] The ammonia injected to the buffer chamber 17 once stay therein,kinetic energies are exchanged, the flow velocities are equalized andthe pressure in the buffer chamber 17 becomes uniform.

[0170] In a state in which the ammonia is introduced into the bufferchamber 17 and a pressure in the space between the pair ofelectrode-protecting tubes becomes uniform, high frequency electricpower from the high frequency power supply 51 is supplied to therod-like electrodes 52 inserted into the two electrode-protecting tubes50 through the RF matching unit 53, plasma 14 is produced between theelectro-deprotecting tubes 50.

[0171] By bringing the ammonia into plasma state in the buffer chamber17, active species of ammonia is produced. At that time, since theplasma is produced in a state in which the pressure in the bufferchamber 17 is uniform, an electron temperature and plasma concentrationdistribution which affect the production of active species also becomeuniform. Therefore, more uniform active species can be produced.

[0172] The active species produced by the effect of plasma has lifetime,and if a distance between a plasma producing portion and the wafer 7 islong, the species are deactivated before they are supplied to the wafers7, and an amount of active species which contribute to the reaction onthe wafers 7 is largely reduced. Therefore, it is preferable that theplasma is produced in the vicinity of the wafers 7.

[0173] According to this structure, since the active species of ammoniais produced in the buffer chamber 17 which is in the vicinity of thewafers 7, it is possible to efficiently supply a large amount of activespecies of produced ammonia to the wafers 7.

[0174] It is preferable that the distance between the twoelectrode-protecting tubes 50 is set to an appropriate value so that aplace where the plasma 14 is generated is limited to inside the bufferchamber 17, and a preferable distance is about 20 mm. The plasma 14 maybe produced anywhere inside the buffer chamber 17, and it is preferablethat the gas introduced into the buffer chamber 17 passes through theplasma. Preferably, the plasma 14 is produced between the buffer chamberhole 3 and the gas supply chamber hole 47.

[0175] A distance between the electrode-protecting tube 50 and thebuffer chamber hole 3 is adjusted to an appropriate value so that theplasma 14 generated in the buffer chamber 17 is not dispersed and leakedoutside the buffer chamber 17.

[0176] As a result, only electrically neutral active species of ammoniaare supplied from the buffer chamber holes 3 to the wafers 7, and it ispossible to avoid the damage caused by charge-up of the wafer 7.

[0177] Since all the buffer chamber holes 3 provided in the bufferchamber 17 have the same opening areas, the active species supplied tothe wafers 7 have uniform flow rates and flow velocities and thus,uniform film forming processing is carried out for the wafers 7.

[0178] Since the buffer chamber holes 3 are located at intermediateportions of the gap between the adjacent wafers 7 placed in themultistage manner, the processing gas is sufficiently supplied to thestacked wafers 7.

[0179] In the ALD method in which different kinds of processing gasesare alternately supplied to form extremely thin films by one layer byone layer, if one layer of the extremely thin film including N atom isformed by supply of the active species of ammonia, the thickness islimited by appropriately setting a pressure or a temperature inside thereaction tube 6, and the thickness of the film is not further increased.

[0180] If the extremely thin film including the N atom is formed on theentire surface of the wafer 7, the supply of RF electric power appliedto the electrode 52 is cut off, and the supply of ammonia is stopped.

[0181] Next, the inside of the reaction tube 6 is purged by inert gassuch as N₂ or Ar and in this state, the gas is exhausted from theexhaust opening 18. If the concentration of the active species ofammonia in the reaction tube 6 has sufficiently reduced, the supply ofthe inert gas is stopped, and dichlorsilane is introduced into thereaction gas buffer chamber 42 from the reaction gas introducing opening45.

[0182] The reaction gas buffer chamber holes 48 whose opening areas aregradually increased from the upstream side toward the downstream side ofthe reaction gas introducing opening 45 are provided in the reaction gasbuffer chamber 42 toward the center of the reaction tube 6. As a result,the dichlorsilane supplied to the wafers from the reaction gas bufferchamber holes 48 has different flow velocities but has the same flowrates and is injected into the reaction tube 6.

[0183] If another set of gas supply chamber 43 and buffer chamber 17which is adjacent to the gas supply chamber 43 which are same as thoseused for supplying ammonia are disposed in the reaction tube 6 insteadof the reaction gas buffer chamber 42, and dichlorsilane is suppliedfrom the buffer chamber holes 3, it is preferable because the flow raterand flow velocities become uniform.

[0184] In this embodiment, if the flow rates of dichlorsilane isequalized using the reaction gas buffer chamber 42 which is more simplethan the combination of the gas supply chamber 43 and the buffer chamber17, it is possible to form sufficiently uniform films on the wafers 7.

[0185] If particles including Si is adsorbed on the wafer 7 in theextremely thin film form, the supply of the dichlorsilane is stopped.Then, the inside of the reaction tube 6 is purged by inert gas such asN₂ or Ar, the gas is exhausted from the exhaust opening 18 and when theconcentration of dichlorsilane in the reaction tube 6 is reducedsufficiently, the supply of the inert gas is stopped.

[0186] A SiNx film of about 1 Å is formed through this series ofprocess. When a SiNx film of 500 Å is to be formed on a wafer 7, theabove process is repeated about 500 times.

[0187] If the boat (not shown) in which the wafers 7 are placed isrotated at a constant speed, even if gas is supplied from a side of thewafers 7, more uniform film forming processing is realized over theentire surfaces of the wafers 7. In this embodiment, the rotating speedof 1 to 10 rpm is sufficient.

[0188] When the boat was not rotated, uniformity of film thickness ofthe wafer 7 is about ±5%, but when the boat was rotated, the uniformitywas <±1%.

[0189] (Third to Fifth Embodiments)

[0190] Different Embodiments Using ALD Method for Film Forming

[0191]FIG. 7 is a lateral sectional view of a reaction tube of avertical type substrate processing apparatus according to a thirdembodiment of the present invention.

[0192] The reaction tube 6 shown in FIG. 7 has the same structure asthat shown in FIG. 6. In FIG. 6, the electrode for producing plasma isdisposed in the buffer chamber 17. In FIG. 7, an ultraviolet lamp 54 foractivating gas and a reflection plate 58 for preventing ultraviolet fromradiating out from the buffer chamber 17 are provided in combination.

[0193] Reaction gas is activated by light energy of the lamp 54.

[0194] The processing gas which is brought into the active species inthe buffer chamber 17 having the above structure is injected toward thewafers 7 from the buffer chamber holes 3, and films are formed on thewafers 7 by the ALD method.

[0195]FIG. 8 is a lateral sectional view of a reaction tube of avertical type substrate processing apparatus according to a fourthembodiment of the invention.

[0196] The reaction tube 6 shown in FIG. 8 has the same structure asthat shown in FIG. 7. In FIG. 7, the reaction gas is activated by lightenergy. In the fourth embodiment, an exotherm (hot wire, hereinafter) 55having appropriate electrical resistance value is heated by a powersupply 57 to a temperature of 1,600° C. or higher, and gas which comesinto contact with the hot wire is activated.

[0197] As the hot wire 55 having the appropriate electrical resistancevalue and generating the active species, a W (tungsten) wire havingabout 0.5 mm or the like can be suitably used.

[0198] This hot wire 55 is heated to 1,600° C. or higher by electricpower of the power supply 57, and processing gas which comes intocontact with the hot wire 55 is activated by the thermal energy.

[0199] The processing gas which is brought into the active species inthe buffer chamber 17 having the above structure is injected toward thewafers 7 from the buffer chamber holes 3, and films are formed on thewafers 7 by the ALD method.

[0200]FIG. 9 is a lateral sectional view of a reaction tube of avertical type substrate processing apparatus according to a fifthembodiment of the invention.

[0201] The reaction tube 6 shown in FIG. 9 has the same structure asthat shown in FIG. 6. In FIG. 6, the plasma generating electrode isdisposed in the buffer chamber 17. In the fifth embodiment shown in FIG.9, a remote plasma unit 56 is disposed on a gas passage upstream fromthe gas introducing opening 5 through which processing gas is introducedinto the reaction tube 6, and gas passing through the remote plasma unit56 is allow to produce plasma.

[0202] The processing gas passing through the remote plasma unit 56 isreacted with plasma and brought into active species, the gas which wasbrought into the active species enters the reaction tube 6 from the gasintroducing opening 5, and is supplied to the buffer chamber 17 throughthe gas supply chamber 43, and is further supplied to the wafers 7 asuniform gas from the buffer chamber holes 3 provided in the bufferchamber 17. Then, films are formed on the wafers 7 by the ALD method.

[0203] An ICP coil or the like is suitably used as the remote plasmaunit 56.

[0204] According to this structure, an amount of active species to besupplied to the wafers is reduced and processing efficiency isdeteriorated as compared with the apparatus shown in FIG. 6. This fifthembodiment is used for a case in which the deterioration in theprocessing efficiency makes no problem.

[0205] (Sixth to Eighth Embodiments)

[0206] Sixth to eighth embodiments of the present invention will beexplained with reference to FIGS. 10, 11 and 12. FIGS. 10, 11 and 12 arelateral sectional views of left halves of reaction tubes 6 used forsubstrate processing apparatuses of the sixth, seventh and eighthembodiments of the invention, respectively.

[0207] In the sixth, seventh and eighth embodiments shown in FIGS. 10,11 and 12, respectively, a gas nozzle 102 is disposed in the bufferchamber 17 from the lower portion to the upper portion of the reactiontube 6 in the stacking direction of the wafers 7. The gas introducingopening 5 is in communication with a lower portion of the gas nozzle102. A large number of gas nozzle holes (not shown) are provided in thegas nozzle 102 in the vertical direction. Like the first to fifthembodiments, the exhaust opening which is in communication with anexhaust pump (not shown) is formed in a side surface of a lower portionof the reaction tube 6.

[0208] In the sixth embodiment shown in FIG. 10, a wall 172 which is aportion of the buffer chamber 17 is a portion of a wall of the reactiontube 6. Two electrode-protecting tubes 50 are disposed closer to a wallsurface 173 of a portion of a wall 171 of the buffer chamber 17 providedwith the buffer chamber holes 3 than a wall surface 174 of the wall 172.Two electrodes 52 protected by the two electrode-protecting tubes 50 arealso disposed closer to the wall surface 173 of the wall 171 than thewall surface 174 of the wall 172. The two electrode-protecting tubes 50are located in the vicinity of the wall 171 of the buffer chamber 17provided with the buffer chamber holes 3 (preferably, a distance betweenthe electrode-protecting tubes 50 and the wall surface of the wall 171of the buffer chamber 17 is 0 to 5 mm. Here, 0 mm means a case in whichthe electrode-protecting tubes 50 are tightly connected to the wallsurface). The two electrodes 52 and the two electrode-protecting tubes50 are disposed astride the buffer chamber holes 3 (that is, the bufferchamber holes 3 are located between the two electrode-protecting tubes50). With this arrangement, a distance between the plasma 14 and thebuffer chamber hole 3 can be shortest.

[0209] If the two electrode-protecting tubes 50 are brought close to thewall surface 173 of the wall 171 constituting the buffer chamber 17, itis possible to limit a main gas flow path. If the buffer chamber holes 3are provided at location where the limited main gas flow path passesbetween the two electrode-protecting tubes 50, the reaction gas canefficiently pass through a region where the concentration of the plasma14 is high, and it is possible to increase the concentration of theactive species.

[0210] In the case of FIG. 10, the reaction gas path in the bufferchamber 17 can roughly be divided into paths D, E, e and f. The paths Dand E are main gas flow path, and most of reaction gas passes betweenthe two electrode-protecting tubes 50, i.e., passes through the regionwhere the concentration of the plasma 14 is high.

[0211] Since the plasma 14 and the buffer chamber holes 3 are locatedvery close to each other, and unnecessary swelling portion becomesminimum. Therefore, deactivation of active species generated in thepaths D and E can be suppressed as low as possible. Even if the activespecies are deactivated before the active species enter the bufferchamber holes 3, the active species can be activated again by the plasma14.

[0212] The paths e and f which do not pass between the twoelectrode-protecting tubes 50 also pass near the plasma 14 just in frontof the buffer chamber holes 3. Therefore, the concentration of theactive species is increased, and deactivation of active species untilthe active species are introduced into the reaction tube 6 is small likethe paths C and D.

[0213] That is, according to this embodiment, the following pointsbecome possible.

[0214] 1) The active species can be activated with plasma having highconcentration (concentration of the active species is increased at thetime of excitation)

[0215] 2) A substrate to be processed (wafer) can be carried withoutdeactivating the active species.

[0216] This embodiment also has a feature that it is unnecessary tocontrol the gas flow paths before the gas is brought into active speciesso that concentration of the active species is not different in thepaths D and E.

[0217] If the electrode-protecting tubes 50 and the buffer chamber 17are brought into tight contact with each other, since the paths e and fare cut off, and the gas paths can be limited to the paths D and E. Thisis effective because the active species having high concentration aresupplied to a substrate. There is no clearance for the paths e and f.This is preferable because there is no variation in concentration ofreaction gas active species between apparatuses.

[0218]FIG. 11 shows the seventh Embodiment. In this embodiment, the gasnozzle 102 and the buffer chamber holes 3 are disposed between the twoelectrode-protecting tubes 50 so that gas supplied from the gas nozzle102 straightly pass through (path F), the plasma 14 and the bufferchamber holes 3. In this structure, the concentration of the activespecies can be increased like the structure shown in FIG. 10.

[0219]FIG. 12 shows the eighth embodiment. In this embodiment, one ofthe two electrode-protecting tubes 50 is brought close to the wallsurface 173 of the wall 171 provided with the buffer chamber holes 3,and the other electrode-protecting tube 50 is brought close to the wallsurface 174 of the portion of the wall 172 of the buffer chamber 17which is the portion of the wall of the reaction tube 6, so that themain gas flow path is limited. The The buffer chamber holes 3 areprovided at locations where the main gas flow path I passes between thetwo electrode-protecting tubes 50.

[0220] If this embodiment shown in FIG. 12 is compared with theembodiments shown in FIGS. 10 and 11, a distance between the plasma 14and the buffer chamber hole 3 becomes long and correspondingly, aswelling portion is generated, but the deactivation can be reduced bybringing one of the electrode-protecting tubes 50 closer to the wallsurface 173 of the wall 171 constituting the buffer chamber 17.

[0221] As described above, the concentration of the active species ofthe reaction gas can be increased by optimizing the layout of the bufferchamber 17, the electrode-protecting tubes 50 and the buffer chamberholes 3.

[0222] The concentration of the active species of the reaction gas canbe enhanced by optimizing the relative position of the buffer chamber17, the electrode-protecting tubes 50 and the buffer chamber holes 3 asdescribed above. When the processing uniformity between apparatuses, thereliability and repeatability are taken into consideration, it ispreferable that there is no variation in the relative position.

[0223] In the above example, since the electrode-protecting tubes 50,the buffer chamber 17 and the buffer chamber holes 3 are independentfrom one another, an assembling error is generated and thus, it isconsidered that the concentration of the active species of the reactiongas is varied between the apparatuses.

[0224] Therefore, if a reaction tube in which the reaction tube 6, awall constituting the buffer chamber 17, the buffer chamber holes 3 andthe electrode-protecting tubes 50 are integrally formed is used, it ispossible to suppress the variation. There is no problem if theseelements are made of quartz and integrally welded to each other.

[0225] In the above example, the positions of the electrode-protectingtubes 50 are explained because the electrode-protecting tubes 50 areused, but when the electrode-protecting tubes 50 are not used, theelectrodes 52 should be located at same positions of theelectro-deprotecting tubes 50.

[0226] If the structures shown in the sixth to eighth embodiments areused, the apparatus can be used as the CVD apparatus like the firstembodiment, and if a buffer chamber 42 is added in addition to thebuffer chamber 17 as shown in FIG. 6, the apparatus can be used as theALD apparatus.

[0227] (Ninth Embodiment)

[0228] A ninth embodiment of the invention will be explained withreference to FIG. 13. In this embodiment, the buffer chamber 42 shown inFIG. 6 is added to the apparatus of the sixth embodiment shown in FIG.10, and the apparatus is formed into the ALD apparatus.

[0229] The gas nozzle 102 is provided with a large number of gas nozzlehole 103 in the vertical direction. The gas nozzle holes 103 is providedtoward a wall surface 176 of a wall 175 of the buffer chamber 17. If gasnozzle holes 103 are provided toward the inside of the buffer chamber 17which is on the other side from the wall surface 176, when siliconnitride films are to be formed using the ALD method by alternatelysupplying ammonia from the gas nozzle 102 and dichlorsilane from thebuffer chamber 42 like the second embodiment, and when ammonia stays anddichlorsilane flows, reaction byproduct is generated, which becomes acause of particles. Therefore, the gas nozzle holes 103 are directedtoward the wall surface 176 of the wall 175 of the buffer chamber 17,and after ammonia is supplied, the chamber is purged with inert gas fornot allowing ammonia to stay and for preventing particles from beinggenerated.

[0230] In the sixth to eighth embodiments, the gas nozzle 102 isprovided at its side surface with the large number of gas nozzle holes(not shown) in the vertical direction. In the ninth embodiment, the gasnozzle 102 is provided at its side surface with the large number of gasnozzle holes 103. The gas nozzle 102 may have a predetermined length,and the gas nozzle holes may be opened at the upper portion of the gasnozzle 102. In this case, it is preferable that a height of the gasnozzle 102 is lower than the loading position of the wafer 7.

[0231] The entire disclosures of Japanese Patent Application No.2002-104011 filed on Apr. 5, 2002 and Japanese Patent Application No.2002-203397 filed on Jul. 12, 2002 including specifications, claims,drawings and abstracts are incorporated herein by reference in theirentireties.

[0232] Although various exemplary embodiments have been shown anddescribed, the invention is not limited to the embodiments shown.Therefore, the scope of the invention is intended to be limited solelyby the scope of the claims that follow.

What is claimed is:
 1. A substrate processing apparatus, comprising; areaction chamber which is to accommodate stacked substrates, a gasintroducing portion, and a buffer chamber, wherein said gas introducingportion is provided along a stacking direction of said substrates, andintroduces substrate processing gas into said buffer chamber, saidbuffer chamber includes a plurality of gas-supply openings providedalong the stacking direction of said substrates, and said processing gasintroduced from said gas introducing portion is supplied from saidgas-supply openings to said reaction chamber.
 2. A substrate processingapparatus as recited in claim 1, wherein opening areas of saidgas-supply openings provided in said buffer chamber are substantiallyequal to each other.
 3. A substrate processing apparatus as recited inclaim 1, wherein said gas introducing portion is provided with aplurality of gas introducing openings along the stacking directions ofsaid substrates.
 4. A substrate processing apparatus as recited in claim1, wherein said gas introducing portion includes a gas-supply tubeprovided in said buffer chamber, and said gas-supply tube is providedwith a plurality of gas introducing openings along the stackingdirection of said substrates.
 5. A substrate processing apparatus asrecited in claim 3, wherein opening areas of said gas introducingopenings of said gas introducing portion are increased from an upstreamside toward a downstream side.
 6. A substrate processing apparatus asrecited in claim 1, wherein said gas-supply openings of said bufferchamber are disposed with the same pitch as that of the stackedsubstrates.
 7. A substrate processing apparatus as recited in claim 1,further comprising another buffer chamber.
 8. A substrate processingapparatus as recited in claim 1, wherein said gas-supply openings ofsaid buffer chamber are provided lower than a position where saidsubstrates are disposed.
 9. A substrate processing apparatus as recitedin claim 1, wherein said buffer chamber is provided therein with a gasactivating member for activating said substrate processing gas.
 10. Asubstrate processing apparatus as recited in claim 9, wherein said gasactivating member is electrodes for generating plasma.
 11. A substrateprocessing apparatus as recited in claim 10, wherein each of saidelectrodes is provided with a protecting member, atmosphere in saidbuffer chamber and said electrodes are not in contact with each other.12. A substrate processing apparatus as recited in claim 11, whereininert gas is charged into said protecting member, or said protectingmember is purged with inert gas.
 13. A substrate processing apparatus asrecited in claim 10, wherein said gas-supply openings of said bufferchamber are provided between said electrodes.
 14. A substrate processingapparatus as recited in claim 1, wherein said buffer chamber is providedin said reaction chamber, said buffer chamber includes first and secondwall surfaces, said gas-supply openings are provided in said first wallsurface of said buffer chamber, said second wall surface of said bufferchamber is a portion of a wall surface of said reaction chamber, saidbuffer chamber is provided therein with electrodes for generatingplasma, and at least one of said electrode is brought closer to saidfirst wall surface than said second wall surface.
 15. A substrateprocessing apparatus as recited in claim 1, wherein said buffer chamberis provided in said reaction chamber, said buffer chamber includes firstand second wall surfaces, said gas-supply openings are provided in saidfirst wall surface of said buffer chamber, said second wall surface ofsaid buffer chamber is a portion of a wall surface of said reactionchamber, said buffer chamber is provided therein with electrodes forgenerating plasma, each of said electrodes is provided with a protectingmember, atmosphere in said buffer chamber and said electrodes are not incontact with each other, and at least one of said electrode is broughtcloser to said first wall surface than said second wall surface.
 16. Asubstrate processing apparatus as recited in claim 1, wherein saidapparatus further comprising a remote plasma unit connected to said gasintroducing portion, said substrate processing gas activated by saidremote plasma unit is introduced into said buffer chamber from said gasintroducing portion.
 17. A substrate processing apparatus, comprising: areaction chamber which is to accommodate stacked substrates, a pluralityof buffer chambers, and a plurality of gas introducing portions forrespectively introducing substrate processing gases to said bufferchambers, wherein said buffer chambers respectively include a pluralityof gas-supply openings provided in a stacking direction of saidsubstrates, and said substrate processing gas introduced from each ofsaid gas introducing portions is supplied to said reaction chamber fromsaid gas-supply openings of each of said buffer chambers.
 18. A reactioncontainer, comprising: a reaction chamber which is to accommodatestacked substrates, a plurality of buffer chambers, and a plurality ofgas introducing portions for respectively introducing substrateprocessing gases to said buffer chambers, wherein said buffer chambersrespectively include a plurality of gas-supply openings provided in astacking direction of said substrates, and said substrate processing gasintroduced from each of said gas introducing portions is supplied tosaid reaction chamber from said gas-supply openings of each of saidbuffer chambers.
 19. A reaction container as recited in claim 18,wherein at least one of said gas introducing portions is provided alonga stacking direction of said substrates.
 20. A reaction container,comprising: a reaction chamber which is to accommodate stackedsubstrates, a gas introducing portion, and a buffer chamber, whereinsaid gas introducing portion is provided along a stacking direction ofsaid substrates, and introduces substrate processing gas into saidbuffer chamber, said buffer chamber includes a plurality of gas-supplyopenings provided along the stacking direction of said substrates, andsaid processing gas introduced from said gas introducing portion issupplied from said gas-supply openings to said reaction chamber.